1. Technical Field
This invention relates to saw blades, and more particularly to circular saw blade having gullets designed to reduce fatigue and increase the life of the blade.
2. Background Information
Conventional circular saw blades typically include a circular steel core having a series of cutters or teeth spaced along the circumference thereof. Gullets, in the form of cutouts extending inwardly from the periphery of the wheel are often interspaced between the cutters to aid cutting, such as by relieving stresses in the blade and for removing swarf. A variety of gullet configurations may be used, including those of generally narrow, wide, and keyhole shapes. The selection of a gullet configuration for a particular saw blade may be based on the cutting application(s) for which the blade is expected to be used.
Saw blades having relatively narrow gullets have been found useful in sawing of construction material with portable power saws, and in other masonry cutting applications on stationary machines, where smooth cutting action is desired. It has been found that the smoothness of cutting action is enhanced when the cutters are placed relatively close to one another, such as provided by the use of relatively narrow gullets. However, cracks tend to propagate from the tightly radiused ends of these gullets, particularly if the blade is exposed to high radial pressure. This problem may be particularly problematic on blades in which a fatigue barrier has been surpassed.
Alternatively, saw blades having relatively wide gullets may be used. These gullets typically have a relatively large radius at their inner ends, which have been found to provide the blade with relatively high fatigue strength. These gullets may thus be beneficial in relatively high-stress cutting environments, such as floor sawing of asphalt or concrete, in which other blade types tend to fail due to stress cracks propagating from the gullets.
Keyhole-shaped gullets attempt to combine the aforementioned benefits of narrow and wide gullets. These gullets enable the cutters of a blade to be positioned relatively close to one another, e.g., to provide a smooth cutting action, while also providing each gullet with a relatively large radius at its radially inner end, e.g., to help reduce crack formation.
While keyhole gullets may exhibit improved characteristics over the narrow and wide gullets in some applications, they are not without drawbacks. For example, results achieved with keyhole gullets have been less than optimal in severe applications involving difficult to cut materials such as steel or a relatively heterogeneous mix of workpiece materials, such as various combinations of masonry and steel materials (e.g., steel reinforced concrete). Under these conditions, cracks have been found to propagate from the ends or sides of the gullets, which may compromise user safety.
Thus, a need exists for a device and method that addresses the aforementioned drawbacks.